SST40 PC board( Because trimmers and jacks are installed on the PC board, there is not
wiring and so it is easy to build. )

Rear panel of my SST( 'FREQ-mite' is fixed by the screw on the upper-left. )( From the left, key, power supply, power supply external / internal switch, antenna, RX RF gain. )
( There are holes on the top plate for speaker addition. )

My SST40 overview (modification points)

Inside of my SST40 before 'FREQ-mite' is installed
（ There are no wiring. )

Inside of my SST40 after 'FREQ-mite' is installed

Major modification points of my SST40 are as follows.

Expansion of the frequency range

Frequency indication using Small Wonder Labs 'FREQ-mite' ( As of May 2015,
we can get it from Four State QRP Group. )

Speaker addition

Upgrading of the filters

Expansion of the frequency range

Two kinds of variable capacitance diodes are included in the SST kit to
select the frequency range when a user build.
In order to make the frequency range wide, I modified my SST to be able
to change the two kinds of variable capacitance diodes with the toggle
switch added on the front panel.

Two kinds of variable capacitance diodes with a toggle switch

A ceramic capacitor from 2 to 4pF is added in parallel to the crystal in
the VXO ( variable frequency crystal oscillator ).

Month, Year

Capacitor added in parallel to the crystal in the VXO

Frequency range( Lower )

Frequency range( Upper )

Remarks

June 2006

None

7.01017～7.01968MHz

7.01799～7.02544MHz

2.5 pF ( two 5pF capacitors in series )

7.00128～7.01782MHz

7.01567～7.02520MHz

Set value in 2006

3pF

6.99882～7.01762MHz

7.01529～7.02521MHz

Jan. 2013

2.72pF ( 5pF and 6pF capacitors in series )

7.00671～7.01939MHz

7.01882～7.02607MHz

3pF

7.00548～7.01908MHz

7.01848～7.02594MHz

4pF

6.99932～7.01822MHz

7.01766～7.02592MHz

Current set value

Pitch frequency and BFO frequency adjustment

The pitch frequency (CW offset) can be adjusted by changing C24.
In order to make the pitch frequency close to 700Hz, C24 was changed from
56pF fixed capacitor to 50pF trimcap and fixed 33pF in parallel.

The BFO frequency can be adjusted by changing C10.
In order to set the center frequency of CW filter passband after product
detector close to 700Hz, C10 was changed from 22pF fixed capacitor to 50pF
trimcap.

Frequency indication

In order to indicate the frequency, Small Wonder Labs 'FREQ-mite' ( As
of May 2015, we can get it from Four State QRP Group. ), a Morse-readout frequency-annunciating device, is installed, and a
push switch is added on the front panel.